Broad band camouflage screen having a frequency dependent radar attenuation

Abstract

A conventional broad-band camouflage material comprising a base layer, a reflective metal layer and a paint layer which imitates the visible and near IR spectral reflective properties of a natural background and contains binders which are transparent in the far IR range, is improved in the radar spectral range by providing the metal layer in the form of spaced squares or rectangles whose long dimension is smaller than 1/2 lambda of the largest radar wavelength used for reconnaissance and larger than 1/2 lambda of the radar wavelength used for homing missiles and bullets. The base layer consists of woven strips of polyethylene material forming squares or rectangles which are metallized on both sides and then covered with polyethylene film coated with liquid polyethylene adhesive. The adhesive fills in the spaces between the strips thus isolating the squares or rectangles from each other and preventing conductivity.

I claim: 
     
       1. A camouflage material having a wide-band effect ranging from the visual portion of the spectrum up through the radar region of the spectrum, said material comprising a base layer consisting of woven strips of polyethylene material forming rectangles or squares whose long dimension is smaller than 1/2 lambda of the largest radar wavelength used for reconnaissance systems and larger than 1/2 lambda of the radar wavelength used for homing missiles and bullets; an intermediate homogeneous metal layer on said base layer reflective in the range of terrestrial thermal radiation as well as in the radar region of the spectrum and having a specific surface resistivity of not more than 0.5 to 10 ohms per square; and an outer camouflage paint layer applied on said reflective metal layer, said paint containing coloring matter having reflective properties in the visible and near IR spectral regions that are similar to the natural background and containing a binder having high transparency characteristics in the spectral regions of the atmospheric windows II (3-5 μm) and III (8-14 μm); wherein the emissivity of the camouflage paint in windows II and III varies over the surface of the material and varies between 50 and 90% in window II and between 60 and 95% in window III and wherein the metal is selected from the group consisting of aluminum, copper, zinc and its alloys. 
     
     
       2. The camouflage material according to claim 1 in the form of garnishing patches having punched slits, and attached to a support net in two planes. 
     
     
       3. The camouflage material according to claim 1, further comprising a thermoplastic layer containing radar absorbing randomly distributed dipoles having semi-conductive properties, said thermoplastic layer being located between said base layer and said reflective metal layer. 
     
     
       4. The camouflage material according to claim 1, wherein length of the rectangles or squares is about 4 to 6 mm and the spaces between the rectangles or squares have a width between about 0.5 and 2 mm so that the transit attenuation for centimeter waves attains a required value. 
     
     
       5. The camouflage material according to claim 4, wherein the length of the squares is about 8 mm and the space between the squares is about 1-2 mm. 
     
     
       6. The camouflage material according to claim 1, wherein the metallic layer is formed on both sides of the base layer. 
     
     
       7. The camouflage material according to claim 6, wherein the coloring matter of the paint comprises thermally transparent colors. 
     
     
       8. The camouflage material according to claim 6 further comprising a film of polyethylene adhered to each metallic layer by means of a liquid polyethylene adhesive. 
     
     
       9. The camouflage material according to claim 8, wherein the adhesive fills in between the strips of polyethylene material so that the rectangles or squares are completely isolated from each other. 
     
     
       10. The camouflage material according to claim 8, wherein the thermally transparent films are stretched polyethylene films stretched perpendicularly to each other.